An etcher is an apparatus used in manufacturing semiconductor devices, which, according to the object of the process, selectively eliminates various thin films such as silicon film, polysilicon film, and silicon oxide film, formed under a photoresist film. The etching may be classified as wet etching using chemicals or dry etching using gas. The etcher apparatus would thus be referred to as a wet etcher or a dry etcher.
FIG. 1 schematically shows the construction of a conventional dry etcher. Referring to FIG. 1, the conventional dry etcher includes a wafer carrier 4, an etching chamber 5, loadlock chambers 6, and a gas discharger 7.
The wafer carrier 4 loads wafers 2 from a wafer cassette 1 and carries the wafers 2 via a conveyer 3 into the loadlock chamber 6. A reaction gas is input into the etching chamber 5, in which a high degree of vacuum is maintained. The loadlock chambers 6 are interconnected to the etching chamber 5 through entrances 5a and 5b. The loadlock chambers 6 are at approximately the same environment as that in the etching chamber 5.
The gas discharger 7 pumps/purges out the reaction gas remaining in the loadlock chamber 6 and etching chamber 5 after the etching process is completed, so as to maintain the high degree of vacuum in the loadlock chamber 6 and etching chamber 5.
When etching polysilicon films and the like by means of the dry etcher as described above, Cl.sub.2, HBr, or the like is usually used as the reaction gas. Such gases exhibit a strong tendency to condense when they are exposed to an atmospheric state. Although, the gas discharger 7 seeks to pump/purge out the reaction gas remaining in the loadlock chamber 6 and etching chamber 5 after the etching process, some portion of the reaction gas still remains that is condensed and liquified on the wafers. The wafers containing the liquified gas are then subjected to the succeeding manufacturing process.
However, such condensed and liquified gas on the wafers must be eliminated because it can degrade the quality of the semiconductor as well as cause downstream manufacturing process problems. Generally, a separate device or a separate process is employed to eliminate the condensed and liquified gas. Such separate devices or processes, however, cause delays in the manufacturing process and increase the cost of manufacturing a semiconductor device.
In light of the foregoing, there exists a need for an etcher and method of preventing gas remaining on a wafer after the wafer is etched from being condensed on the wafer, without having to resort to a separate device or a separate treatment method.